This invention relates to self-service shopping, and in particular to a methodology for improving the security of a self-service shopping system by the use of statistical sampling of shoppers and their purchases.
Self-service shopping systems are desired for their ability to offload service-oriented functions from human labor forces and provide automatic assistance to the shopper for increase in response time, efficiency, throughput, lower cost, and the like. For example, systems in the prior art provide each shopper with a portable bar code scanning device, which is used to scan the bar code located on a product in order to determine the price by accessing a locally stored look-up table and keep a tally list of all items selected for purchase. When the shopper is finished selecting items for purchase and scanning the bar codes on the items, he places the self-scanner into a recess in a stationary (i.e., wall-mounted) cradle, wherein a list of items selected is printed out for a receipt and provided to the shopper. The shopper then brings the list along with the cart of selected items to a clerk for tender of final payment and, possibly, an audit of items selected for purchase in order to ensure that all items selected and placed in the cart were properly scanned. This self-service scenario speeds shoppers through the store quicker than the conventional conveyor belt/cashier environment typical in stores today.
Security in a self-service shopping system as described above is a major concern of retailers. Shoppers who fail to scan the bar code of an item placed in their shopping cart will bring the item home without proper payment, whether such failure to scan the item is intentional or inadvertent. In addition, shoppers may scan an item but place a different (i.e. more expensive) item in their cart. Therefore, some methodology of checking shoppers' purchases must be implemented in order to satisfy security criteria.
Two goals of a self-checkout system are to increase shopper throughput and to save in labor costs. Ideally, a shopper can scan his items when selected from the shelf and save scanning time at the checkout line. In addition, stores would require less human labor since there is a reduction in the number of cashiers required. However, there is still a requirement to scan some items from a shopper's cart if a shopper is determined to be audited in order to flag an attempted theft as well as to provide deterrence against pilferage. Thus, some labor is required to scan at least some of the items leaving the store. At one extreme, a system where every shopper has all of his purchase items re-scanned is not feasible since there is no net time savings in such a system (all purchases are scanned by a cashier anyway). There is therefore a need to determine whether a shopper needs to be audited and how many and which items are to be scanned in order to maximize the potential for catching pilferage, provide maximum deterrence against theft, minimize labor costs in checking the shoppers' scanned items, maintain the increased throughput achieved by the self-checkout system, and avoid the negative inferences inherently made by shoppers whose items are checked by an exit cashier or security guard.
Prior art proposals for checkout security require a cashier to check only certain shoppers, but to scan their entire cart full of goods. This type of system is unsatisfactory for those shoppers who are selected for full checking, since they must wait for the entire cart to be re-scanned (thus defeating the purpose of the self-checkout system), suffer potential embarrassment at being singled out by the store for security checking, etc. Thus, an entirely new methodology is needed to supplant this security checking system.